Well my ongoing Tracs and no Speedometer continues, I guess nobody here has had the same issue, at least in the sense that the obvious doesn't resolve it.
Well NOW, the car wouldn't start 3 times today, a door shutting vigorously, was enough to regenerate life, prior to that everything was dead, the clock reset and so on. excuse me but, wtf, how can this happen, what the hell can be so loose as to be rectified by vibration from the door. The battery and its terminals are fine.
I give up with this piece of rubbish, and while I'm ranting, it no way compares with the relaibility of Omega's I owned in the UK.
Are you getting the ABS light on? If whichever of the rear abs sensors isn't "seeing" the toothed ring, then the speedo wont work. Getting underneath and cleaning any muck off of the sensors and checking any electrical connectors might resolve this issue.
Your door slamming problem might be down to a dodgy connection on the ignition switch barrel or a loose multiplug on the back of the dashboard. http://www.omegaowners.com/forum/YaBB.pl?num=1152618876